Vista mpx spectrometer

The biosorption of Mn(II) ions was carried out according to the procedure described by Michalak and Chojnacka.²³ In brief, the experiments were performed in Erlenmeyer flasks containing 500 mL of Mn(II) ions solution in a shaker at 200 rpm (IKA KS 260 basic; IKA^® Works, Inc). The biomass content in the solution was 5 g/L (C_S). The solution of Mn(II) ions with the initial concentration of 300 mg/L (C₀) was prepared in deionized water by dissolving appropriate amount of the MnSO₄·H₂O salts (from Avantor Performance Materials Poland SA). The initial pH of the solution was adjusted to 5, according to our previous studies,²³ with 0.1 M NaOH/HCl (from Avantor Performance Materials Poland SA) using pH‐meter Mettler Toledo (Seven Multi) equipped with an electrode InLab413 with compensation of temperature. The biosorption time was 4 hours. After the process, the solution was filtered through filter paper (Macherey‐Nagel, Mn 615). Manganese solution before and after biosorption process was analysed using ICP–OES method (inductively coupled plasma‐optical emission spectrometry) using Varian VISTA MPX spectrometer in the laboratory of Multielemental Analyses at Wrocław University of Science and Technology, which is accredited by ILAC‐MRA and Polish Centre for Accreditation (no. AB 696). The enriched with Mn(II) ions biomass was subjected to the extraction process.

Overnight liquid cultures of H. pylori strain were grown until OD₆₀₀ 0.9 at 37°C in 6 ml Brucella-Broth with FCS, then 10 μM or 100 μM NiCl₂ were added and the cultures were left to grow until OD₆₀₀ 6. Then, the 6 ml of culture were centrifuged at 4000 g at 4°C for 25 min through 400 μL of a 1:2 mixture of the silicone oils AR20/AR200 (Wacker) in order to separate the cells from the medium. Cells were lysed with 400 μL 0.2 M NaOH/1% SDS for 60 min at 95°C. Samples were calibrated by protein concentration measurements with the DC Protein Assay kit (BioRad). Then, the samples were mineralized overnight at 80°C with 300 μL of ultrapure 70% nitric acid (JT Baker) and diluted to 1/20 in ultrapure water. Nickel contents were measured by ICP-OES using a Vista MPX spectrometer (Varian). The content of Ni(II) was determined using a curve established with certified ICP grade standards. The measurement of each strain in each condition was performed in triplicates in at least two independent experiments.